Steam pressure reducing valves are type of self operated valve that can auto reduce the downstream pressure of steam and self adjust the amount of valve opening to allow the pressure to remain the same even if the flow rate changes by pistons, springs or diaphragms. The pressure reducing valve adopts the opening and closing parts inside the PRV body to adjust the flow of the fluid, reduce the fluid pressure and adjust the opening degree of the opening and closing parts with the help of the pressure behind the valve, then the pressure behind the valve remains in a certain range, in the case of constant changes in the inlet pressure to keep the outlet pressure in the pre set range. To choose the right type of steam pressure reducing valve is very important. This leads to another question why steam needs pressure-reducing?
Steam sometimes causes condensation, and condensed water loses less energy at low pressure. The steam after decompression reduces the pressure of condensate and avoids the flash steam when it is discharged. The temperature of saturated steam is related to pressure. In the sterilization process and surface temperature control of paper dryer, pressure relief valves are needed to control the pressure and further control the temperature. Some systems are with high-pressure condensate water to produce low-pressure flash steam to achieve the purpose of energy-saving when the flash steam is insufficient or steam pressure exceeds the set value where needs a pressure reducing valve.
The types of steam pressure reducing valve
There are many types of steam pressure reducing valve, they can be divided into direct-acting pressure reducing valve, piston pressure reducing valve, pilot-operated pressure reducing valve and bellows pressure reducing valve according to their structure.
Direct-acting pressure reducing valve has a flat diaphragm or bellow and does not need to install external sensing lines downstream because it is independent. It is one of the smallest and most economical pressure reducing valves, designed for the medium with low flow and stable load. The accuracy of direct-acting relief valves is usually +/-10% of the downstream set point.
